فصلنامه زیست فناوری میکروبی
پیاپی 8 (بهار 1390)

The use of natural antimicrobial compounds indenting herbal medicine and flavorings in preserving foods has been widely devoted. These compounds other than antimicrobial characteristic have antioxidant and flavoring characteristics. The other hand probiotic products by reducing the risk of heart attacks and recovering favorable microbial flora of digestive tract have an extraordinary effect on consumer's health status. This survey was done in order to evaluate the effect of thymus on lactobacillus acidophilus and Bifidobacterium bifidum as the starter bacteria of probiotic yoghurt. To determine the effect of thymus different doses (0%, 0.03%, 0.06% and 0.09%) on the growth of probiotic bacteria, Bifidobacterium bifidum and lactobacillus acidophilus in the first stage (milk) and the second stage, 0.33 grams of lyophilized Bifidobacterium bifidum and lactobacillus acidophilus separately was added to one liter of sterilized low fat milk. In on other experiment, a mixture of two bacteria, in an amount of 0.165, was done according to the above steps. The samples were evaluated on the basis of pH, acidity and microbial count in the warm holding and preservation periods. In the tenth day of production the products were evaluated under organoleptic tests. The results of questionnaires were and used in the descriptive analytic test and by the use of SPSS software. The results showed that in the samples containing two bacteria we have got the best results related to the taste, preservation and color. Bioavailability of probiotie bacteria was counted by the use of direct counting method. In a 15 day period, the number of bacteria was decreased and also no statistically meaningful difference was observed between the control samples and the samples containing different concentrations of thymus.

Group A Streptococci is one of the most important bacteria which is capable of causing sore throat among children. Since A Streptococcal sore throat can lead to various diseases such as rheumatic, it is a potentially serious medical problem and adequate treatment is imperative. The aim of the present study was to determine the incidence of sore throat caused by group A Streptococci among 5-15 years age children referred to Children Emergency Department at Beasat hospital during six month. A total of 266 Children which were among 5-15 years old (150 male and 116 female) with the sore throat sings who referred to Children Emergency Department at Beasat hospital, Sanandaj were investigated in this study. After taking the swab samples, bacteria was isolated and identified and also tested for its antibiotic susceptibility pattern. From 266 samples, incidence of sore throat was 25.5 %, out of which 42 were boys and 26 were girls. Their mean age was 9.3 years. Incidence of sore throat among 5-7 years age 33.8%, and in 8-10 years age group was 26.5 %. The antibiotic susceptibility pattern showed that Group A Streptococci was 28.3, 25.8 and 24.6% resistant to Carbinicillin, Ampicillin and Tertracycline respectively. Similarly, Gentamycin, Ceftriaxone, Ciprofolxacin, Corti were highly active against them. Group A Streptococci is the most important cause of sore throat among Children who refereed to Children Emergency Department at Beasat hospital, Sanandaj. All the Streptococci isolates were resistance to the very common antibiotics. Therefore, there should be a continuous surveillance system regarding antibiotic susceptibility pattern.

Extensive use of hexavalent chromium in various industrial applications has caused substantial environmental contamination and the toxicity occurs in human due to environmental pollution via soil and water or due to occupational exposure because of these adverse effects, the EPA has identified Cr (VI) as one of the seventeen chemicals posing the greatest threat to human health. Bacteria can reduce chromate to the insoluble and less toxic Cr (III). The aim of this study was evaluated of chromate bioremediation with use of Cr (VI) reduce microbial enhancement of efficiency process of detoxification of Cr (VI) to Cr (III). 241 Chromium resistant bacteria isolated from industrial wastewater of Qom were examined for their tolerance to hexavalent chromium and their ability to reduce Cr (VI) to Cr (III). The influence of various factors such as pH, time interval, temperature, aeration and initial metal concentrations on the reduction of chromium by the high tolerant bacterial isolate was studied. A Gram-positive chromate reducing bacterial strain was isolated from effluents of textile, and identified as Staphylococcus arlettae strain R8-6A by phenotypic characterization and 16S rRNA analysis. Staphylococcus arlettae strain R8-6A could tolerate up to 770 mM of chromate and 93.6% reduced 0.3 mM highly toxic and soluble Cr(VI) (as Cr2O4) into almost non-toxic and insoluble Cr(III) in 48 h under aerobic condition. The maximum chromate removal were exhibited in Initial Cr(VI) concentration until 0.3 mM at 35 °C, pH 6.5 and 50 rpm. The results indicate that the microbial consortia and the mono cultures of the above isolates can be useful for Cr (VI) bioremediation of chromium contaminated environment.

Brucellosis is a zoonotic disease which has an extremely economic importance. Prevention and diagnosis of human and cattle infected with the organism both are challenging researches. Immunologic evaluation of diverse antigens of Brucella cells has a key role in development of prevention and diagnosis programs. Here, we report the production and immunologic evaluation of recombinant 18kDa outer membrane lipoprotein of Brucella abortus (Omp19). Brucella omp19 gene was amplified with PrimSTAR® HS DNA polymerase, cloned in pJET1.2 and sequenced. The omp19 gene was cut by BamHI and HindIII from confirmed vectors and subcloned in pET28a(+). pET28a(+) vectors cloned with omp19 were transformed into E. coli BL21(DE3) as expression host. Expression of recombinant protein was induced by IPTG and verified by western-blotting. Recombinant protein was purified using Ni-NTA resin and was applied to detect antibodies in human and animal brucellosis cases serum samples via western-blotting. Recognition of antibody to the recombinant Omp19 (rOmp19) in serum samples of infected cases suggests the stimulation of immune response to this protein during brucellosis. The study indicates rOmp19 of Brucella abortus is an appropriate antigen for further investigations in vaccines and serologic diagnosis programs.

Rhizobia variants are groups of bacteria that fix nitrogen synergistically with root of Leguminaceae. The aim of this study is growth enhancement of Alfalfa plants using native Sinorhizobium isolates. Alfalfa plants were collected and confirmed by an expert. The nodules were crushed and inoculated to yeast extract manitol agar. The isolated bacteria were confirmed by inoculation test of alfalfa seeds in Leonard jar. Disinfected seeds of Alfalfa (Medicago sativa) var Hamedani were cultured in big pots (90 × 30 with 25cm high) in similar temperature, watering, light, and moisture. Plants in four tested pots were watered by bacterial suspension of four isolates of bacteria on third day and two cases were used as controls. After a six-week watering period by free nitrogen nutrient solution, plants were pulled out from soil and compared for their growth and nitrogen rate. Molecular confirmation of these isolates was carried out by amplification (PCR) of a specific gene named mucR. Control plants had no nodules and plants inoculated with Sinorhizobia had nodules. Ten plants of each pot were separated randomly and significant differences were observed between plant length, stem and root length of control and symbiosis plants. Dried weight of a hundred of control plants was 0.35g and for symbiosis plants were 1.12, 1.07, 0.79 and 0.78g. The rate of nitrogen was less in control than symbiosis plants. The results of this study show that four native isolated Sinorhizobium caused the enhancement of alfalfa plants and have potential for use as biologic fertilizer. It seems isolate No. 2 enhances the growth of plants more effectively than other isolated bacteria.

Hepatitis B virus infection prevalence is more significant in hemodialysis patients than the others. Serological HBV detection techniques could not detect the infection in early stages. On the bases of common detection methods limitations, molecular detection techniques like PCR are more useful in hemodialysis patients. In this study it has tried to applied PCR technique for the detection of HBV Virus in hemodialysis patient's serums. 136 serum samples were obtained from patient who referred to three in hemodialysis centers in Tehran. DNA was extracted by using DNP kit. The sensitivity and specificity of test were performed and after that was done on samples. PCR product was electrophoresed in 1.5% agarose gel. Amplicon (262 bp) cloned by PCR-cloning and then sequenced by dideoxy chain termination. PCR test had high specificity which no reaction was seems to the other infectious agents DNA except Hepatitis B virus DNA. The PCR sensitivity up to 40 particles was observed. Among the 136 serum samples 11 cases (8.09%) were PCR positive in our study, but only 1 case were ELISA positive. The compression between ELISA and PCR application on hemodialysis patients suggested that the employed assay system constitutes an effective tool for the rapid diagnosis of Hepatitis B virus especially in hemodialysis patients. In addition because of low serological techniques sensitivity for detection, it seems PCR could be an appropriate replacement for these detection techniques.

Aflatoxins are the most important mycotoxin that produced by fungi. Some strains of LAB can control mutagens factors like aflatoxin. It seems that it is because of physical attachment between LAB and mutagens. The aim of this study is evaluation ability of 32 lactobacilli strains isolated from Tarkhineh to attach and remove aflatoxin from buffer solution by ELISA. An overnight culture of each lactobacilli (1010 CFU/ml) was transferred into PBS buffer with 5µg/ml aflatoxin. After 2h incubation cells were removed by centrifuge and remained aflatoxin was assessed by ELISA. In order to control all physicochemical factors temperature were kept in 37ºC in neutralized condition. The strains were observed to possess variable AFB2-binding ability in the range from 8.4 to 89.9%. Most efficient binding of AFB1 was observed by isolatesTD2, TD14, and TD15 while T1 and T5 showed the least capacity. Our results indicated that Lactobacillus strains isolated from Tarkhineh could sequestrate of aflatoxin by binding the toxin in a strain dependent manner. So After more safety assessment these isolates can be used in food industry as a native probiotic.

A greater understanding of how the survival of Lactobacillus acidophilus cells in the process of preparing and using it commercially as a probiotic bacterium is useful. So, the aim of this study is determination of the effect of different environmental stresses on survival of L. acidophilus.As L. acidophilus is one of the most important probiotic microorganisms in food technology, so we decided to review different aspects of stress responses in L. acidophilus in published papers between 1980 and 2010.Results showed that L. acidophilus has possibility to adapt to one or more stresses, but not all stresses could provide cross-protection against every stresses tested. It appears that L. acidophilus is capable of displaying adaptive response to stress. It also proved that the resistance of L. acidophilus against stress in the stationary growth phase is more than the logarithmic growth phase.Considering the factors studied in this research L. acidophilus bacteria has possibility to adapt to against environmental stress and can be treated before using it in harsh conditions, in order to bacteria survival increase.